I am quite sorry for spamming this post however, my last two inquiries on the GOG downloader discussion and The Witcher's forums have been fruitless. I'm not entirely sure if this is the place to ask but, when downloading, or attempting to download, The Witcher, I get the error message "You do not have access to this product". I have tried switching web browsers with no luck.
Has anybody else received this message? If so, please tell me how you managed to fix it.

Weird...

Assuming you have purchased the game - the best advice I can give you is a support ticket: http://www.gog.com/en/support/contact

I did purchase the game since I can download it through my browser. The GOG downloader seems to be the real problem.

are you logged-in in the downloader?

Hmm, that's odd. You might try deleting the downloader and redownloading it. Sounds like the account information is stale.